A reboiler stable operation system in a POSM process

Abstract

The utility model discloses a kind of reboiler stable working systems in POSM process, it is related to chemical technology field, including rectifying column, reboiler, column top condenser, reflux tank, reboiler forced circulation pump and reflux pump;The top of rectifying column is connected with the inlet of column top condenser by column top gas phase pipeline, and tower top pressure gauge is installed on the pipeline, and the side of rectifying column is connected with the bottom inlet of reboiler by a group of feed pipe, reboiler feed regulating valve is installed on the feed pipe, the top outlet of reboiler is connected with rectifying column by feed pipe, to form thermal siphon loop in this way.The design can safely, quickly, smoothly speed up the efficiency of reboiler thermal siphon establishment, shorten high-pressure propylene column operation cycle, avoid the security risk that propylene material mass leakage exists.Simultaneously, shorten the device driving process to some extent, reduce the consumption of material consumption, energy consumption during start-up and shutdown, save driving input capital.

Description

Technical Field

[0001] This utility model belongs to the field of chemical technology, specifically, it relates to a stable working system for a reboiler in a POSM process. Background Technology

[0002] The main raw materials for the POSM co-production process are ethylene, benzene, propylene, etc. The process mainly includes peroxidation, epoxidation, propylene oxide refining, ethylbenzene recovery, acetophenone hydrogenation, toluene alcohol dehydration, and styrene refining.

[0003] In the POSM co-production process, the efficient and stable operation of the high-pressure propylene tower is crucial to the overall operation of the POSM system. Its main function is to purify propylene, the feedstock for the epoxidation reaction, and ensure the conversion rate of the epoxidation reaction. Therefore, the ability of the high-pressure propylene tower to quickly establish a thermosiphon is a key factor affecting the start-up progress of the entire process.

[0004] During normal operation, the thermosiphon of the reboiler in a high-pressure propylene tower is driven by the density difference between the propylene / PO and ethylbenzene / MBA media before and after vaporization at the reboiler inlet and outlet. However, during initial startup, the system lacks PO / MBA and other components, with only propylene and ethylbenzene present at the bottom of the tower. The reboiler inlet and outlet media have a single composition, and while propylene readily vaporizes upon steam heating, the steam cannot readily vaporize ethylbenzene. Therefore, a density difference cannot be established between the reboiler inlet and outlet, making thermosiphon establishment difficult. Propylene exists as a light component in the tower; if thermosiphon cannot be established, normal mass and heat transfer will be impossible. When the light propylene enters the reboiler, its vaporization absorbs a large amount of heat, causing a rapid contraction of the reboiler head. This leads to failure of the reboiler head sealing surface, resulting in propylene leakage and posing a significant safety risk.

[0005] The existing thermosiphon setup process is extremely unstable, and due to poor thermosiphon performance, the reboiler is prone to flooding. Frequent large-scale propylene leaks from the reboiler during start-up and shutdown significantly increase safety risks, prolong the start-up process, and increase capital investment.

[0006] No effective solutions have yet been proposed to address the problems in the relevant technologies.

[0007] Therefore, in order to solve the above problems, this utility model provides a stable working system for the reboiler in the POSM process. Utility Model Content

[0008] In order to overcome the above-mentioned technical problems, the purpose of this utility model is to provide a stable working system for reboilers in POSM processes.

[0009] The objective of this utility model can be achieved through the following technical solutions: A stable reboiler operating system in a POSM process includes a distillation column, a reboiler, a column top condenser, a reflux tank, a reboiler forced circulation pump, and a reflux pump; The top of the distillation column is connected to the inlet of the top condenser via a top vapor pipeline, and a top pressure gauge is installed on this pipeline. The lower side section of the distillation column is connected to the bottom inlet of the reboiler via a set of feed pipes, and a reboiler feed regulating valve is installed on this feed pipe. The top outlet of the reboiler is connected to the distillation column via a feed pipe, thus forming a thermosiphon loop. The bottom of the distillation column is equipped with a bottom outlet pipe, which is a T-shaped tee structure. A bottom outlet valve is installed on its vertical section, and a column bottom level control valve and a forced circulation pump inlet valve are installed at both ends of its horizontal section, respectively. The end with the forced circulation pump inlet valve is connected to the inlet of the reboiler forced circulation pump. The outlet of the reboiler forced circulation pump is connected to the reboiler feed pipe at a 45° downstream direction via a connecting pipe, and merges with the downstream of the reboiler feed regulating valve. A forced circulation pump outlet valve is installed on this connecting pipe. The bottom of the condenser at the top of the column is connected to the top of the reflux tank via a connecting pipe. The bottom of the reflux tank is connected to the inlet of the reflux pump via a reflux pipe. The outlet of the reflux pump is connected to the main reflux pipe. The main reflux pipe branches into two branch pipes. One branch pipe is connected to the upper reflux port of the distillation column as the normal reflux path. The other branch pipe is connected to the connecting pipe at the outlet of the reboiler forced circulation pump. The branch pipe is equipped with a first forced circulation line valve and a second forced circulation line valve, forming a backup forced circulation path driven by the reflux pump.

[0010] As a preferred embodiment of this utility model, a top thermometer for monitoring the internal temperature of the distillation column is installed at the top of the column, a bottom thermometer is installed in the middle of the column body, a bottom level gauge is installed in the lower half of the distillation column, and a bottom thermometer is installed at the bottom of the distillation column.

[0011] As a preferred embodiment of this utility model, a top pressure control valve is installed on the top gas phase pipeline of the distillation column.

[0012] As a preferred embodiment of this utility model, a reboiler inlet thermometer is installed on the feed pipe connecting the distillation column and the reboiler. A steam inlet pipe is connected to one side of the reboiler, and a steam control valve is installed on the pipe. A steam condensate outlet pipe is also connected to one side of the reboiler, and a condensate collection control valve is installed on the pipe. A reboiler outlet thermometer is installed on the feed pipe connecting the reboiler and the distillation column.

[0013] As a preferred embodiment of this utility model, the bottom end of the tower top condenser is connected to a water inlet pipe, and a cooling water inlet valve is installed on the pipe. The top end of the tower top condenser is connected to a water return pipe, and a cooling water return valve is installed on the pipe. A condenser outlet thermometer is installed on the connecting pipe between the tower top condenser and the reflux tank.

[0014] As a preferred embodiment of this utility model, a reflux pump inlet valve is installed on the reflux pipe between the reflux tank and the reflux pump, a reflux pump outlet valve is installed on the reflux main pipe on one side of the reflux pump, a reflux tank level gauge is installed on one side of the reflux tank, and a reflux tank pressure gauge is installed on the top of the reflux tank.

[0015] Compared with the prior art, the present invention has the following beneficial effects: In this invention, technical improvements are made to the existing process. A pipeline is added before the regulating valve on the tower bottom discharge pipeline, connecting to an additional set of small-flow, high-head reboiler forced circulation pumps. The outlet of the reboiler forced circulation pump is connected to the reboiler inlet pipeline at a 45° counter-current direction. A pipeline is added from the reflux pump outlet to the reboiler inlet, connecting to the outlet pipeline of the reboiler forced circulation pump, serving as a backup forced circulation line for the reboiler. Simultaneously, a regulating valve is added to the existing reboiler inlet pipeline to control the liquid flow rate at the reboiler inlet, thereby accelerating the establishment of the reboiler thermosiphon. This design safely, quickly, and smoothly accelerates the establishment of the reboiler thermosiphon, shortens the start-up cycle of the high-pressure propylene tower, and avoids the safety risks associated with large-scale propylene material leakage. Furthermore, it shortens the start-up process to a certain extent, reduces material and energy consumption during start-up and shutdown, and saves on start-up investment. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0018] Figure label: 1. Distillation column; 11. Top pressure gauge; 12. Top thermometer; 13. Bottom thermometer; 14. Bottom level gauge; 15. Bottom thermometer; 16. Bottom discharge valve; 17. Bottom level control valve; 18. Top pressure control valve; 2. Reboiler; 21. Reboiler feed regulating valve; 22. Steam control valve; 23. Condensate collection control valve; 24. Reboiler inlet thermometer; 25. Reboiler outlet thermometer; 26. Forced circulation pump outlet valve; 27. Forced circulation pump inlet valve; 28. First forced circulation line valve; 29. ​​Second forced circulation line valve; 3. Top condenser; 31. Cooling water inlet valve; 32. Cooling water return valve; 33. Condenser outlet thermometer; 4. Reflux tank; 41. Reflux pump inlet valve; 42. Reflux pump outlet valve; 43. Reflux tank level gauge; 44. Reflux tank pressure gauge; 5. Reboiler forced circulation pump; 6. Return pump. Detailed Implementation

[0019] The utility model will now be further described with reference to the accompanying drawings and specific embodiments: Please see Figure 1 According to an embodiment of the present invention, a stable reboiler operating system in a POSM process includes a distillation column 1, a reboiler 2, a top condenser 3, a reflux tank 4, a reboiler forced circulation pump 5, and a reflux pump 6. The distillation column 1 is the core separation equipment, providing a place for material separation. The bottom material provides the circulation and heat source basis for the reboiler. The reboiler 2 provides vaporization heat for the distillation column and is the core equipment for thermosiphon. The top condenser 3 condenses the top gaseous material, providing liquid material for reflux and subsequent processes. The reflux tank 4 stores the condensed liquid phase, balances the system pressure, and provides a stable feed for the reflux pump 6. The reboiler forced circulation pump 5 provides forced circulation power at the beginning of operation, quickly pushing the bottom material into the reboiler and accelerating the establishment of thermosiphon. The reflux pump 6 not only ensures the top reflux of normal production but also serves as a backup forced circulation power source for the reboiler 2, improving system reliability. The top of distillation column 1 is connected to the inlet of the top condenser 3 via a top vapor pipeline, and a top pressure gauge 11 is installed on this pipeline. The lower side section of distillation column 1 is connected to the bottom inlet of reboiler 2 via a set of feed pipes, and a reboiler feed regulating valve 21 is installed on this feed pipe. The top outlet of reboiler 2 is connected to distillation column 1 via a feed pipe, thus forming a thermosiphon loop. A bottom discharge pipe is installed at the bottom of distillation column 1. The bottom discharge pipe has a T-shaped tee structure, with a bottom discharge valve 16 installed on its vertical section and a column discharge valve installed at both ends of its horizontal section. The bottom liquid level control valve 17 and the forced circulation pump inlet valve 27 are installed, and one end of the forced circulation pump inlet valve 27 is connected to the inlet of the reboiler forced circulation pump 5. The outlet of the reboiler forced circulation pump 5 is connected to the feed pipe of the reboiler 2 at a 45° downstream direction through a connecting pipe, and merges with the downstream of the reboiler feed regulating valve 21. The forced circulation pump outlet valve 26 is installed on the connecting pipe. By setting the reboiler forced circulation pump 5 and its connecting pipe, the bottom material of the tower can be forcibly pushed through the reboiler 2 in the initial stage of start-up when thermosiphon is difficult to establish naturally, providing initial circulation power. The bottom of the top condenser 3 is connected to the top of the reflux tank 4 via a connecting pipe. The bottom of the reflux tank 4 is connected to the inlet of the reflux pump 6 via a reflux pipe. The outlet of the reflux pump 6 is connected to the main reflux pipe. The main reflux pipe branches into two branch pipes. One branch pipe is connected to the upper reflux port of the distillation column 1 as the normal reflux path. The other branch pipe is connected to the connecting pipe at the outlet of the reboiler forced circulation pump 5. The branch pipe is equipped with a first forced circulation line valve 28 and a second forced circulation line valve 29, which constitute a backup forced circulation path driven by the reflux pump 6. The backup forced circulation pipeline from the outlet of the reflux pump 6 to the reboiler 2 provides another guarantee or transition means during the establishment of thermosiphon or under specific operating conditions.

[0020] Please see Figure 1 The distillation column 1 is equipped with a top thermometer 12 to monitor the internal temperature of the column. A bottom thermometer 13 is also installed in the middle of the column. The top thermometer 12 and the bottom thermometer 13 are used to monitor key temperature parameters inside the distillation column 1, reflecting the distillation effect and the establishment of thermosiphon. A bottom level gauge 14 is installed in the lower half of the distillation column 1 to monitor the bottom level and ensure sufficient material for circulation and heating. A bottom thermometer 15 is installed at the bottom of the distillation column 1, which directly reflects the temperature state of the material in the bottom. The top thermometer 12, bottom thermometer 13, bottom level gauge 14, and bottom thermometer 15 together provide operators with a basis for judging the degree of thermosiphon establishment and adjusting operating parameters, ensuring the safe and stable operation of the system.

[0021] Please see Figure 1A top pressure control valve 18 is installed on the top gas phase pipeline of distillation column 1. The setting of the top pressure control valve 18 ensures effective control of the column pressure, providing conditions for the establishment and stable operation of thermosiphon.

[0022] Please see Figure 1 A reboiler inlet thermometer 24 is installed on the feed pipe connecting the distillation column 1 and the reboiler 2. A steam inlet pipe is connected to one side of the reboiler 2, and a steam control valve 22 is installed on this pipe. A steam condensate discharge pipe is also connected to one side of the reboiler 2, and a condensate collection control valve 23 is installed on this pipe. A reboiler outlet thermometer 25 is installed on the feed pipe connecting the reboiler 2 and the distillation column 1. By controlling the feed flow rate, steam heating amount, and monitoring the inlet and outlet temperatures, the thermosiphon establishment speed is accelerated. The reboiler outlet thermometer 25 is used to visually judge the thermosiphon establishment status and optimize the parameters in a timely manner.

[0023] Please see Figure 1 The bottom of the top condenser 3 is connected to a water inlet pipe, on which a cooling water inlet valve 31 is installed. The top of the top condenser 3 is connected to a return water pipe, on which a cooling water return valve 32 is installed. A condenser outlet thermometer 33 is installed on the connecting pipe between the top condenser 3 and the reflux tank 4. By adjusting the cooling water, the gas phase at the top of the tower is condensed to a suitable temperature, providing qualified liquid phase material to the reflux tank 4 and assisting in the establishment of thermosiphon.

[0024] Please see Figure 1 A reflux pump inlet valve 41 is installed on the reflux pipe between reflux tank 4 and reflux pump 6. A reflux pump outlet valve 42 is installed on the reflux main pipe on one side of reflux pump 6. A reflux tank level gauge 43 is installed on one side of reflux tank 4. A reflux tank pressure gauge 44 is installed on the top of reflux tank 4. The reflux tank level gauge 43 and the reflux tank pressure gauge 44 ensure the stability of the liquid level and pressure in reflux tank 4, providing a guarantee for the start-up and operation of reflux pump 6, thereby supporting the smooth operation of the reflux process and the backup forced circulation process.

[0025] The working principle of a reboiler stabilization system in a POSM process is as follows: Open the cooling water inlet valve 31 and cooling water return valve 32 of the condenser at the top of the tower. The bottom level gauge of distillation column 1 feed column is 14% to 50-80%; When the liquid level in the distillation column reaches 50-80%, open the reboiler feed regulating valve 21 to feed the reboiler 2. Open the steam feed valve 22 to heat the reboiler 2; The steam condensate from reboiler 2 is controlled by condensate extraction control valve 23. Open the bottom discharge valve 16, close the bottom liquid level control valve 17, open the forced circulation pump inlet valve 27, start the reboiler forced circulation pump 5, open the forced circulation pump outlet valve 26 of the reboiler forced circulation pump 5, and establish forced circulation in the reboiler 2. The thermosiphon effect of reboiler 2 can be observed by reboiler outlet thermometer 25. When reboiler outlet thermometer 25 gradually rises, it indicates that thermosiphon is established. At this time, the thermosiphon effect of reboiler 2 can be increased by adjusting the opening of reboiler feed regulating valve 21 and steam control valve 22 until reboiler outlet thermometer 25 rises to 115-200℃. Distillation column bottom thermometer 13: temperature 50-85℃; Top thermometer 12: temperature 35-55℃. As the thermosiphon of reboiler 2 is gradually established, the column pressure is increased to 1.2-2.0 MPaG by controlling the column top pressure control valve 18; The temperature of the top thermometer 12 is 35-55℃. The gaseous material enters the top condenser 3 through the top gas pipeline. The temperature after condensation is monitored by the condenser outlet thermometer 33. The temperature of the condensed liquid phase is controlled between 27-50℃; The liquid material condensed to 27-50℃ by the top condenser 3 enters the reflux tank 4 for storage. The reflux tank 4 is equipped with a reflux tank level gauge 43 to monitor the liquid level and a reflux tank pressure gauge 44 to monitor the pressure. The return tank level gauge 43 shows a level of 35-60%. Start the reflux pump 6, and open the reflux pump outlet valve 42, the first forced circulation line valve 28, and the second forced circulation line valve 29; Turn off the reboiler forced circulation pump 5 and establish a forced circulation process from the outlet of the reflux pump 6 to the reboiler 2; The temperature at the bottom of the column (thermometer 15) is 100-135℃, the outlet temperature of reboiler 2 is 115-200℃, the temperature at the bottom of the column is 50-85℃, the temperature at the top of the column (thermometer 12) is 35-55℃, and the pressure at the top of the column (pressure 11) is 1.2-2.0 MPaG, indicating that the thermosiphon of reboiler 2 is fully established. Close the first forced circulation line valve 28 and the second forced circulation line valve 29 of the reflux pump 6 to the reboiler 2; Establish a reflux process from reflux pump 6 to distillation column 1.

[0026] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0027] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A reboiler stable operation system in a POSM process, characterized in that: It includes a distillation column (1), a reboiler (2), a column top condenser (3), a reflux tank (4), a reboiler forced circulation pump (5), and a reflux pump (6). The top of the distillation column (1) is connected to the inlet of the top condenser (3) via a top vapor pipe, and a top pressure gauge (11) is installed on the pipe. The lower side of the distillation column (1) is connected to the bottom inlet of the reboiler (2) via a set of feed pipes, and a reboiler feed regulating valve (21) is installed on the feed pipes. The top outlet of the reboiler (2) is connected to the distillation column (1) via a feed pipe, thereby forming a thermosiphon loop. A bottom outlet pipe is installed at the bottom of the distillation column (1), and the bottom outlet pipe is T-shaped. The structure is a three-way valve with a bottom discharge valve (16) installed on its vertical section. The two ends of its horizontal section are respectively equipped with a bottom liquid level control valve (17) and a forced circulation pump inlet valve (27). The end with the forced circulation pump inlet valve (27) is connected to the inlet of the reboiler forced circulation pump (5). The outlet of the reboiler forced circulation pump (5) is connected to the feed pipe of the reboiler (2) at a 45° downstream direction through a connecting pipe and merges with the downstream of the reboiler feed regulating valve (21). The forced circulation pump outlet valve (26) is installed on the connecting pipe. The bottom end of the top condenser (3) is connected to the top end of the reflux tank (4) through a connecting pipe. The bottom end of the reflux tank (4) is connected to the inlet of the reflux pump (6) through a reflux pipe. The outlet of the reflux pump (6) is connected to the reflux main pipe. The reflux main pipe branches into two branch pipes. One branch pipe is connected to the upper reflux port of the distillation column (1) as the normal reflux path. The other branch pipe is connected to the connecting pipe of the outlet of the reboiler forced circulation pump (5). The branch pipe is equipped with a first forced circulation line valve (28) and a second forced circulation line valve (29), which constitute a backup forced circulation path driven by the reflux pump (6).

2. The reboiler stable operation system in a POSM process according to claim 1, characterized in that: The distillation column (1) is equipped with a top thermometer (12) for monitoring the internal temperature of the distillation column (1), a bottom thermometer (13) is installed in the middle of the column body, a bottom level gauge (14) is installed in the lower half of the distillation column (1), and a bottom thermometer (15) is installed at the bottom of the distillation column (1).

3. The reboiler stable operation system in a POSM process according to claim 1, characterized in that: The distillation column (1) is equipped with a top pressure control valve (18) on the top gas phase pipeline.

4. The reboiler stable operation system in a POSM process according to claim 1, characterized in that: A reboiler inlet thermometer (24) is installed on the feed pipe connecting the distillation column (1) and the reboiler (2). A steam inlet pipe is connected to one side of the reboiler (2), and a steam control valve (22) is installed on the pipe. A steam condensate discharge pipe is also connected to one side of the reboiler (2), and a condensate collection control valve (23) is installed on the pipe. A reboiler outlet thermometer (25) is installed on the feed pipe connecting the reboiler (2) and the distillation column (1).

5. A POSM process reboiler stable operation system according to claim 1, characterized in that: The bottom end of the tower top condenser (3) is connected to a water inlet pipe, on which a cooling water inlet valve (31) is installed. The top end of the tower top condenser (3) is connected to a return water pipe, on which a cooling water return valve (32) is installed. A condenser outlet thermometer (33) is installed on the connecting pipe between the tower top condenser (3) and the reflux tank (4).

6. The reboiler stable operation system in a POSM process according to claim 1, characterized in that: A reflux pump inlet valve (41) is installed on the reflux pipe between the reflux tank (4) and the reflux pump (6). A reflux pump outlet valve (42) is installed on the reflux main pipe on one side of the reflux pump (6). A reflux tank level gauge (43) is installed on one side of the reflux tank (4). A reflux tank pressure gauge (44) is installed on the top of the reflux tank (4).

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